1. Field of Invention
The present invention relates to an electro-optical device using an active matrix addressing method. More particularly, the present invention relates to an electro-optical device including an intermediate conductive layer which serves to provide a good electrical connection between a pixel electrode and a pixel switching thin film transistor (hereinafter also referred to as a TFT), and which is formed as one of layer of a multilayer structure formed on a substrate.
2. Description of Related Art
In a conventional electro-optical device using TFTs as active matrix addressing elements, when a scanning signal is applied to the gate electrode of a TFT via a scanning line, the TFT is turned on, and an image signal applied via a data line to the source region of the semiconductor layer is supplied to a pixel electrode via that TFT. Because the period during which an image signal is supplied to each pixel electrode via a TFT is very short, a storage capacitor is generally added to each pixel electrode to retain an image signal supplied to each pixel electrode over a period of time much longer than the period of time during which the TFT is in the ON state.
In this type of electro-optical device, various conductive films serving as scanning lines, data lines and the like and a gate insulating film and an interlayer insulating film for electrically isolating the conductive films from each other are formed in a multilayer between a conductive film such as an ITO film serving as a pixel electrode and a semiconductor layer of a TFT serving as a pixel switching element. Thus, the distance between the pixel electrode and the semiconductor layer is as large as about 1000 nm. This makes it difficult to electrically connect the pixel electrode and the semiconductor layer with each other via only a single contact hole. One known technique of solving the above problem is to form an intermediate conductive layer between interlayer insulating films so that the pixel electrode and the semiconductor layer are electrically connected to each other via this intermediate conductive layer.